To be honest, I am not sure whether I think that's true. Since our only example from canon is Tonks it's hard to say whether you can fully appear to become any animal, like an Animagus (who though can only achieve one animal form). The vast majority of the time she changes her human appearance, although she did, what, a pig nose in OotP.
Anyway, it's neither here nor there. I suppose I only meant Teddy is not a werewolf. I suspect he could have a wolf Patronus in keeping with the dead people thing. ;)